Various types of knee braces are shown in the patent literature and are commercially available. The following constitute examples of prior art braces that deal with restricting anterior movement of the tibia found in the following U.S. Pat. Nos: 4,751,920 (Mauldin et al.); 4,781,180 (Solomonow) and 4,955,369 (Bledsoe, et al).
The apparatus shown by Mauldin is a knee brace that has a first attachment portion to attach the brace to the wearer's thigh and a second attachment portion to attach the brace to the wearer's tibia and a hinge connected to the medial side of the first and second attachment portions by way of a thigh bar and tibia bar, respectively. An adjustable gearing mechanism located at the hinge permits the wearer to limit the amount of rotation of the tibia bar with respect to the thigh bar. However, this brace suffers from failing to be able to prevent anterior translation of the tibia by the application of posterior pressure directly at the tibia tubercle location. Instead, like its predecessors, the Mauldin apparatus attempts to limit tibial rotation by limiting medial hinge motion.
The apparatus shown by Solomonow is a knee brace having an upper framework attached to the thigh and a lower framework attached to the lower leg just below the knee. These two frameworks are hinged on the medial and lateral sides of the leg (bilateral hinge). A bell crank is pivotally connected to the lower framework. An adjustable screw coupled to one side of the bell crank engages an offset portion of the upper framework whenever the leg is extended. The other side of the bell crank is coupled to a tibial restraining strap. As the leg is extended, the lower framework and bell crank are rotated counterclockwise until the offset of the upper framework contacts the screw, rotating the bell crank in a clockwise direction and thereby tightening the tibial restraining strap against anterior movement of the tibia.
The apparatus shown by Bledsoe et. al is a knee brace which also utilizes bilateral hinges to connect the thigh support and calf support sections. The bilateral hinges basically comprise adjustable drive plates that alternate the pivoting point of the thigh support and calf support throughout leg flexion and extension. By varying the pivot point at different points throughout leg extension, a counter shearing force is generated to reduce the shearing force created by the quadriceps muscle which cause the undesirable anterior shift of the tibia of the leg.
Examples of prior art knee braces which are commercially available are: DONJOY 4-Point.TM., GoldPoint.TM. and Playmaker.TM. all of which are sold by Smith & Nephew Donjoy Inc. of Carlsbad, Calif.; Innovation Sports C.T.I. Standard, Super-Light and Pro-Start, C.T.I..sup.2, MVP and Sentry all of which are sold by Innovation Sports of Irvine, Calif.; Cincinatti ACL which is sold by Brace Technologies Inc. of Cincinatti, Ohio; OS-5.TM. which is sold by Omni Scientific, Inc. of Martinez, Calif.; and the Lennox Hill.TM. OTS and Spectralite which are sold by 3M Health Care of Long Island City, N.Y. Many of the foregoing braces, while suitable for their intended purposes nevertheless suffer from a common problem, namely, they fail to adequately restrict abnormal anterior tibial movement. All of these conventional braces, basically, comprise a top cuff (or pad), a bottom cuff (or pad), a hinge in the middle (located on the medial side, lateral side or on both of these sides of the leg, i.e., bilateral hinge) and straps to affix the brace to the leg. Although such configurations are satisfactory for dealing with side-of-the-knee injuries, these braces permit the natural motion of the leg which means that they also do not prevent anterior translation of the tibia.
Another type of knee disorder that is common in adolescent males is known as Osgood Schlatter's Disease (OSD). OSD is the partial tearing of a growing tibial tubercle, manifested by subcutaneous swelling over the tibial tubercle and is aggravated by running or by kneeling on, or sustaining direct blows to, the tibia tubercle location. A conventional method of treating OSD is by the use of a device known as a Cho-Pat strap which is sold by Cho-Pat, Inc. of Hainesport, N.J. This strap alleviates the pain associated with OSD by maintaining the patella out of the way of the irritated area. In particular, the strap encompasses the entire circumference about the knee, just under the patella. The disadvantage of this device is that it must be tied tightly about the knee, cutting off blood flow to the calf causing cramping. Moreover, because the strap encompasses the entire circumference of the knee, it tends to bind or encumber the knee location whenever the wearer bends his knee, i.e., it is uncomfortable during sitting or squatting.
Another type of knee disorder is an untracked patella. In a normal knee, as the knee is bent, the patella orients itself into the trochlear groove. When the leg is extended, the patella emerges from that groove. In some cases during this extension, this removal from the trochlear groove makes the patella vulnerable by going out of socket. To guide the patella and ensure that it tracks freely and smoothly, the conventional means used is, in essence, a sleeve with a hole located at the patella which surrounds the knee cap. However, the disadvantage of this design is that as the leg is extended, i.e., when the patella is most vulnerable, the hole puckers, thereby reducing tension applied around the knee cap. Reduction in tension during extension is just the opposite of what is needed: one wants tension to increase around the knee cap as the knee is extended in order to keep the patella aligned.